Beginning with seeds

Starting lobelia from seed requires considerable patience, since seeds are slow to germinate (15 to 20 days), and you may not have seedlings large enough to plant outdoors until two months from sowing.

Plant lobelias in moist, rich soil. In hottest areas they need partial shade, but in mild coastal climates they’ll take full sun.

Germinate at 24 degrees Celsius (75 degrees F). Do not cover seed. Usually germinates in 2 to 3 weeks. Professional growers should use a fungicide to control damp-off. Transplant in small clumps or use multi seed pellet.
In mild climates, you can continue planting lobelia through late spring and into summer. Where seasons are short, try to get them into the garden as early as possible, once danger of frost is past. Plants will self-sow if conditions suit them.